In a medium bowl, sift together the flour, spices, salt and baking soda. Set this aside.

Beat butter and sugar together until light and fluffy. Add the eggs, one at a time, beating well and scraping down the sides after each. Add the vanilla and beat until combined. Add a 1/3 of the flour, followed by half of the yogurt, beating after each addition. Repeat: flour, yogurt, flour. Fold in the blackberry preserves (lumps are yummy).

Pour into the prepared pan and bake for 15 minutes. Leaving the cake in and the door closed, increase the heat to 350 and bake for 40-50 minutes more, till nice and brown, and a toothpick inserted comes out clean. Cool in the pan for 10 minutes, then turn it out onto rack to cool completely before glazing.

For the glaze heat the 1/2 cup of blackberry preserves in a small sauce pan (or the microwave) until it thins a bit, then whisk in the powdered sugar till thick and smooth. Pour over cake. (Make sure you have something under it to catch all that drippy glaze!)